Weight scales and strain gauge assemblies useable therein

ABSTRACT

A strain gauge assembly of the type having an elongate flexible member (12) with attached strain gauges (36, 38) has forces applied thereto at points (48, 50) spaced from its central neutral plane (52) by means including members mounted to a foot (10) and force receiving (14) members for non-sliding lateral movement relative thereto. In another embodiment strain gauges are attached to a flexible diaphragm (68) which is in communication with a fluid contained within a flexible sealed container (78) that is restrained against lateral movement by a hollow restraint member (62) therearound but which has a portion (80) protruding from a lower open end (66) thereof to receive a load to pressurize the fluid for flexing the diaphragm (68). A weight scale suitable for employment of the above strain gauge assemblies has an electronic adder (91) summing the loads of a plurality of strain gauge assemblies (92) or load modules to produce a total load signal which is applied to an electronic display (90) for provision of a visual indication of weight.

BACKGROUND OF THE INVENTION

This invention generally relates to weight scales and, moreparticularly, to electronic weight scales and strain gauge assembliesused therein.

Electronic weight scales are well known which employ strain gauges thatare attached to a flexible member. Compression or stretching of thestrain gauge during flexing of the member causes it to produce a voltagewhich is related to the load, or weight, causing the member to flex.This voltage is then amplified and applied to an LED or other suitabledisplay for visually indicating the weight placed on the scale.

In particular, it is known to employ an elongate flexible, cantileveredbeam which is tightly secured to a rigid frame at one end and whichreceives a load intermediate the secured end and its distal end thatcauses it to flex and thereby energize a strain gauge attached thereto.In order to prevent excessive flexing, it is often necessary to providethe flexible, cantilevered beam with a substantial thickness whichprevents incorporating it in a scale of desirable low profile.Customarily, the load is applied to the beam at a single fixed pointspaced a substantial relative distance from the fixed end which definesa single movement arm. The precise length of this movement arm iscritical for accurate measurement but is difficult to achieve. Inaddition, non-linearity in the relationship between the load and amountof resultant flexing is caused by the flexing. As the beam flexes more,an increasing large component of the load force becomes directed alongthe length of the beam instead of transverse to the beam. Further, sincethe force is applied to only one point on the beam, uniform distributionof the load to this one point is difficult to achieve.

An electronic scale is known which alleviates some of these problems butwhich has other disadvantages. In this electronic scale, the ends of anelongate flexible member with a strain gauge are torqued, or rotated, inopposite direction to cause the intermediate portion of an elongateflexible member to flex downwardly in response to a load. The ends passthrough slots through intermediate portions of elongate, loaddistribution arms which are caused to twist about their elongate axis inresponse to a load. These arms are supported on one side by knife edgesupports and receive loads at their other sides through knife edge loadtransmission members to cause them to twist and thus apply a torque tothe ends of the flexible member at the edges of the slots.

This approach may enable a lower profile than the cantilevered structurenoted above and achieves a certain degree of load distribution by virtueof the spaced, elongate arms. However, position of the flexible memberrelative to the edges of the slots in the arms is not fixed andnon-linearities are still introduced. Such non-linearities areintroduced in part because of high friction sliding movement between thearms and the flexible member which resist flexing to an increasingdegree with increasing loads. In addition, the flexing of the membercauses apparent foreshortening between the load points which introducesfurther non-linearities.

A further problem with known weight scales is that only the scalehousing protectively encloses the relatively fragile strain gauges.Accordingly, the strain gauges are relatively unprotected prior toassembly or during repair when the housing is removed. In addition,known scales are constructed in a way which does not facilitatesubstantial sub-assembly of modular units and the cost reducingadvantages resultant therefrom.

SUMMARY OF THE INVENTION

It is therefore a principal object of the present invention to provideweight scales and strain gauge assemblies which solve or alleviate theproblems and disadvantages of known electronic scales and strain gaugeassemblies.

In keeping with this objective, a weight scale having a housing and adisplay responsive to a strain gauge signal for visually indicatingweight measured by the scale is provided with an improved strain gaugeassembly comprising a flexible member with a strain gauge attachedthereto to provide an electrical signal in response to the flexing ofthe flexible member, a foot member in underlying relationship with theflexible member, a load receiving member in overlying relationship withthe flexible member, a pair of support members connected with the footmember for supporting the flexible member at a pair of spaced locationsassociated therewith, and a pair of load transmitting members connectedwith the load receiving member for transmitting a load therefrom to theflexible member at two locations spaced from one another and from thepair of locations associated with the foot member.

In a preferred embodiment, a strain gauge assembly is providedcomprising a foot member, a load receiving member, a flexible memberwith a strain gauge attached thereto and means for interconnecting theflexible member with the foot member and the load receiving memberincluding an interconnecting member mounted between the flexible memberand at least one of the foot member and the load receiving member formovement relative thereto.

Preferably, an interconnecting support member is mounted to the footmember for rocking movement relative thereto and an interconnectingforce transmitting member is mounted to the force receiving member forrocking movement. This rocking movement substantially reduces the amountof frictional force resisting the movement of the flexible memberrelative to sliding movement. Accordingly, the movement is smoother andmore responsive to the flexing of the flexible member. This reducesnon-linearity otherwise caused by high frictional force in known straingauge assemblies.

Another objective of the present invention is to provide a strain gaugeassembly with means for compensating for the inherent forshortening ofthe flexible member between the points of application of force. Unlikeknown devices, this is achieved by making connection of support membersand force transmitting members at fixed locations on the flexible memberoffset from the neutral plane and spaced from the surface of theelongate member. This reduces the amount of movement required by themovable support members and force transmitting members and therebyreduces the frictional force resisting movement of the flexible member.This thus further reduces non-linearity.

In a preferred embodiment, a strain gauge assembly is provided with aframe member, a flexible member having a pair of opposite surfacessubstantially equidistant from a central neutral plane thereof, a firstnotch extending from one of the surfaces to within a preselecteddistance from the central plane and a second notch extending from theother of the surfaces to within another preselected distance from thecentral plane, a strain gauge mounted to one of the surfaces, a pair ofsupport members mounted to the frame member and extending into the firstnotch to support the flexible member at the preselected distance fromthe central neutral plane, means for transmitting a load to the flexiblemember including a load receiving member in overlying relationship withthe flexible member and a load transmitting member mounted to the loadreceiving member and extending into the second notch to transmit forcereceived by the load receiving member to the flexible member at theother preselected distance from the central neutral plane. Preferably,the preselected distances are equal to one another.

It is also an objective of the present invention to provide a straingauge sub-assembly comprising an elongate flexible member having a pairof surfaces equidistant from a central neutral plane thereof, a straingauge mounted to at least one of the pair of surfaces, and a pair ofnotches in each of the pair of surfaces extending into the flexiblemember to a preselected distance from the netural plane.

Yet another object of the present invention is to provide a strain gaugeassembly in which the flexible member and strain gauges are protectivelyenclosed by the foot member and load receiving member which interconnectto form a self-contained module. In keeping with this objective, in apreferred embodiment, a strain gauge assembly is provided that comprisesa load receiving member having an open face opposite a main wall betweena pair of spaced sidewalls, a foot member having an open face opposite amain wall between a pair of sidewalls, a flexible member with a straingauge attached thereto and means connected with the main walls of theframe member and load receiving member for mounting the flexible memberin force receiving relationship therebetween and protectively enclosedby both of said pairs of sidewalls. Preferably, additional pairs ofsidewalls are provided which interconnect the first mentioned pair ofsidewalls to form the load receiving members and frame members intorectangular boxes, one of which interfits within the other. In thisfashion, the strain gauge, support and load transmitting members andflexible member are protectively surrounded by sidewalls. Thisconstruction also improves the rigidity of the load receiving member andthe foot member.

It is also an object of the present invention to provide an electronicweight scale having a housing and display mounted to the housing forproviding a visual indication of weight in which an improvement isprovided comprising a plurality of self-contained load modules, each ofwhich includes a strain gauge for sensing weight, an electronic adderconnected with each of the strain gauges of the plurality of loadmodules for producing a total weight signal proportional to the totalweight sensed by the strain gauges and means for connecting the averageweight signal to the display to cause visual display of the averageweight represented thereby. This approach overcomes the problems ofweight distribution and averaging attempted by mechanical means in knowndevices.

Still another object of the present invention is to provide a straingauge assembly which employs a flexible diaphragm and means forreceiving and uniformly distributing a load to the diaphragm. Thisobjective is achieved by provision of a weight scale having a housing inwhich the improvement is a combination of elements mounted to thehousing, comprising, a load receiving member, a flexible member with astrain gauge attached thereto, a sealed, flexible, fluid containercontaining a fluid in pressure communication with the flexible member,means for increasing the pressure in the container to flex the flexiblemember in response to application of a load to the load receivingmember, and means responsive to the strain gauge for providing anindication of weight.

Preferably, such a strain gauge assembly is provided with a lateralrestraint member having a pair of opposite upper and lower open ends, aflexible diaphragm having a strain gauge attached to a surface thereofto provide an electrical indication of weight, means for mounting thediaphragm to the restraint member to close the upper end, a sealedflexible container of a fluid having a portion partially containedwithin the restraint member and in pressure communication with theflexible diaphragm at the upper end and another portion protruding fromthe lower open end to support the restraint member above a floor surfaceagainst the load and means spaced from the flexible diaphragm forapplying a downwardly directed load to the restraint member, such loadcausing the flexible container to be pressed upward by the sealedflexible container to apply fluid pressure to the diaphragm in relationto the load.

Another object of present invention is to provide a weight scalecomprising a plurality of self contained load modules having a straingauge for sensing weight in response to loading of a flexible fluidcontainer, means for electronically adding the weight sensed by thestrain gage for producing a signal representative of the total weightand means for displaying a visual indication of the total weight inresponse to the signal.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing objects, features and advantages will be described ingreater detail, and further objects, features and advantages will bemade apparent in the detailed description of the preferred embodimentswhich is given with reference to the several views of the drawing, inwhich:

FIG. 1 is a cross sectional side view of a preferred embodiment of oneform of the strain gauge assembly of the present invention;

FIG. 2A is a sectional end view of the strain gauge assembly taken alongsection line II--II of FIG. 1;

FIG. 2B is a plan view of a portion of the flexible member and footmember which more clearly illustrates the restraint member shown in FIG.1;

FIG. 3 is a schematic illustration of the flexing of a flexible memberresulting from the application of forces to the neutral plane thereof;

FIGS. 4A and 4B are schematic illustrations of the encircled area ofFIG. 3 of prior to and after flexing, respectively, to illustrate theresultant apparent foreshortening of the flexible member which thepresent invention is designed to overcome;

FIGS. 5A and 5B are schematic illustrations of the flexible member ofthe strain gauge assembly of the present invention before and afterflexing, respectively, and illustrating the manner in which theforeshortening problem is overcome;

FIG. 6 is a cross sectional side view of another embodiment on a straingauge assembly of the present invention which employs a flexiblediaphragm instead of an elongate flexible member;

FIGS. 7A and 7B are schematic illustrations of the location of thestrain gauges on the flexible diaphragm of the strain gauge assembly ofFIG. 6 at tensive and compressive sections of the diaphragm;

FIG. 8 is a schematic illustration of a weight scale employing thestrain gauge assemblies, or load modules, of FIGS. 1 or 6; and

FIG. 9 is a schematic illustration of another form of the weight scaleof the present invention employing the strain gauge assemblies, or loadmodules, of FIG. 1 or 6.

DETAILED DESCRIPTION

Referring now to the drawings, particularly FIGS. 1 and 2A, the flexiblemember strain gauge assembly of the present invention is seen to includean underlying rigid, foot, or frame, member 10, an elongate flexiblemember 12, an elongate rigid force, or load, receiving member 14, a pairof underlying support members 16 and 18 and a pair of force transmittingmembers 20 and 22. The foot member 10 has a rectangular bottom plate 24and two pairs of opposite sidewalls 26 and 28 surround its perimeter toform an open box. Similarly, the rigid force receiving member 14 has anupper force, or load, receiving rectangular plate 30 with two pairs ofdownwardly extending, opposite sidewalls 32 and 34 interconnected aroundthe perimeter to form another open box. As seen, the box of forcereceiving member 14 is larger than the box of foot member 10 and fitsover it so that the sidewalls 26, 28, 32 and 34 and rectangular plates24 and 30 protectively envelop and surround the remaining portion of thestrain gauge assembly. In addition to this protective feature, thebox-like configuration of the foot member 10 and force receiving member14 also advantageously increases their rigidity.

A pair of strain gauges 36 and 38 are respectively mounted to a pair ofopposite surfaces 40 and 42 of flexible member 12. These semiconductorstrain gauges 36 and 38 are located intermediate, preferably centrally,of support members 16 and 18 and have pairs of leads 44 and 46. Thesepairs of leads extend from the strain gauges within the protectiveenclosure formed by foot member 10 and force receiving member 14 towithout the enclosure for connection with external circuitry. As is wellknown, when the semiconductor strain gauges 36 and 38 are compressed ortensed upon application of a load to the force receiving member whichcauses the flexible member to flex, they produce a resultant voltagewhich is related thereto. This voltage is produced across the pairs ofleads 44 and 46 to develop a signal representative of the load appliedto the strain gauge assembly.

In keeping with another important aspect of the present invention, theflexible member 12 has two pairs of notches 48 in underlying surface 42and a pair of notches 50 in overlying surface 40. Both of these pairs ofnotches extend from their respective surfaces to a preselected distanceX from a central neutral plane 52 extending through the center of theflexible member 12. The support members 16 and 18 and force transmittingmembers 20 and 22 have knife edges which extend into these notches andthe forces applied thereby are thus applied to the flexible member 12 atthis preselected distance X from the neutral plane 52.

This advantageously alleviates the problems resulting from apparentforeshortenting of the flexible member 12 when it is flexed asillustrated in FIGS. 3, 4A and 4B. Referring to FIG. 3, an elongateflexible member has notches similar to those shown in FIG. 1 but whichextend to the neutral plane 12. Accordingly, the distance A between thepoint of application of the load force L by the transmitting member 20or 18 and the point of application of the resultant force R by thesupport member 16 or 22, respectively, varies due to the flexing ofneutral plane 12.

Referring to FIG. 4A, when the load force and resultant force is zero ora very small value such that there is no significant flexing, thedistance between the points of application of the load force L andresultant force R is a certain preselected distance "a" measured in alateral direction parallel to the elongate directions of foot member 10and force receiving member 14. However, referring to FIG. 4B, after asufficient load force L and resultant force R is developed to causeflexing of the neutral plane 12, the distance between the points ofapplication of these forces to the neutral plane measured in the lateraldirection is reduced to a distance "a'" which is less than distance "a".

Consequently, since the foot member 10 and force receiving member 14 arerigid and do not flex, to the extent that one of the support members andone of the force transmitting members does not laterally move to followthe lateral movement of the point of the notch the load force l andresultant force R is applied to the flexible member 12 in a directionwhich is offset by an angle b that is offset from the transversedirection to the force receiving member 14 and foot member 10. To theextent that one of the support member and associated force transmittingmember and the associated support member is resisted by friction,flexing of the flexible member is restrained. Accordingly, as the loadis increased and the flexible member 12 flexes more and more andfriction increases, an increasing component of the load force isdirected in a non-transverse direction which results in a non-linearrelationship between the load force and degree of flexing. That is, thegreater the flexible member 12 is flexed, the greater the amount offorce is required for a further increment of flexure.

Referring to FIGS. 5A and 5B, in the present invention this problem issubstantially alleviated by application of the load and resultant forcesto the flexible member 12 at a preselected distances X1 and X2 offsetfrom the neutral plane 52 as illustrated in FIG. 5A. As seen in FIG. 5B,this additional distance X from the neutral plane creates acorresponding additional distance a1" and a2" at opposite ends of thesegment of the flexible member 12 between the point of application ofthe load force and the resultant force. When these are added to theforeshortened distance a' between points of application at the neutralplane maintenance of an overall distance "a" is achieved. Accordingly,the amount of movement of the movable support member and forcetransmitting member is reduced, and the friction associated with suchmovement, sliding or otherwise, is thereby eliminated. Preferably,distances X1 and X2 are equal to each other and thus distances a1" anda2" are equal.

Referring again to FIG. 1, another advantageous feature of the presentinvention is the provision of a movably mounted support member 16 and amovably mounted force transmitting member 22 which are mounted to theirassociated foot member 10 and force receiving member 14 for non-slidingmovement therealong. Again, due to the apparent foreshortening of theflexible member when flexed, it is necessary that at least one of thesupport members or its associated force transmitting member be permittedto move laterally as the flexible member is flexed. While movementbetween members by sliding one laterally relative to the other wouldwork in the present structure, it is not preferred. When heavy loads areapplied, this sliding motion is resisted by high frictional forces whichimpede free movement and thus impede the proper and free flexing of theflexible member in response to the load. Thus, again as the load isincreased, each additional increment of flexing requires a greaterincrement of force to overcome the frictional force.

This problem caused by high friction and the resultant non-linearity ispreferably alleviated in accordance with the present invention byproviding a support member 16 and a force transmitting member 22 whichis designed to non-slideably move along the surface of its associatedfoot member 10 and force receiving member 14. Preferably, thisnon-sliding movement is a pivotal, rocking movement although a rollingmovement is also contemplated. In particular, referring to FIG. 1, eachof the movable support members 16 and force transmitting member 22 havean elongate knife edge member 54, the distal end of which extends intothe associated notch. The distal end is supported above a base member 56having an arcuate surface, preferably circular, to provide for rockingmotion. Alternatively, the base is provided with underlying ballbearings or the like for rolling motion. The frictional force resistingthe rocking or rolling motion is, of course, substantially less than thefrictional force to overcome sliding movement, and thus linearity issubstantially enhanced. The remaining support member 18 and forcetransmitting member 20 may have a base 58 fixedly attached to itsassociated foot member 10 or force receiving member 14 and a knife edgeportion 60 extending into the associated notch.

Referring to FIGS. 1, 2A and 2B, four restraint members 53 are providedfor holding together the assembly of the foot member 10, flexible member12 and the load receiving member 14 in the absence of a load. Theserestraint members are in the form of resilient straps made of plastic orthe like and are mounted directly over the associated notches 48 and 50.Two of them have their opposite ends 55 mounted to the opposite sides ofthe foot member and extend over the top surface 40 of the flexiblemember to hold the flexible member 12 against the support members 16 nd18 in the absence of a load. Knife edges 57 fit into small grooves 59 inthe top surface 40 at the opposite sides thereof to restrain theflexible member 12 and foot member 10 against relative lateral movement.The other pair of restraint members have their opposite ends 55 mountedto the opposite sides of the load receiving member and extend over thebottom surface 42 of the flexible member 12 against the loadtransmission members 20 and 22. Likewise, knife edges 61 fit intogrooves at opposite sides of surface 42 to prevent relative movement.

Referring now to FIGS. 6, 7A and 7B, another embodiment of a straingauge assembly employing a flexible diaphragm instead of an elongateflexible member will be described. The strain gauge assembly of FIG. 6comprises a hollow restraint member 62 having an upper open end 64 andan opposite lower open end 66. This restraint member is rigid andresists movement in a direction transverse to the direction between itsopen ends. A flexible diaphragm 68 has a pair of strain gauges 70 and 72attached to an upper surface thereof to provide an electrical signalindicative of weight. Each of these strain gauges 70 and 72 have a pairof leads 74 for connection with external circuitry. The metal diaphragm68 is mounted around its periphery to the hollow restraint member 62 bymeans of a member 76 which clamps it against the upper end of restraintmember 62 to close the open end 64. A sealed flexible container 78 madeof rubber, flexible plastic or the like contains a fluid, such as oil,which is in pressure communication with the underside of diaphragm 68.

Preferably, the flexible membrane 68 closes the open end of the flexiblecontainer 78 and the fluid is in direct pressure communication, asshown. Alternately, the flexible container has a sealed top and thefluid is in indirect pressure communication with the flexible membraneby pressing the upper portion of the flexible container surface againstthe membrane. The sealed flexible container 78 is substantiallycontained within the confines of the restraint member 62 which restrainsit from lateral movement. However, it has a portion 80 which protrudesfrom the lower open end 66 to support the restraint member 62 above afloor surface 82 against a load L. A member 76 which extends around theperiphery of restraint member 62 and clamps both the diaphragm 68 and aperipheral lip portion 84 of flexible container 78. This member 76 alsofunctions to transmit a load force L to the restraint member 62 and thusto sealed flexible container 78 from a force receiving and distributionmember 86.

When a load L is applied to force receiving and distribution member 86,the bottom surface of the protruding portion 80 of sealed flexiblecontainer 78 is pressed upwardly which is translated into an increase influid pressure that causes the diaphragm 68 to flex upwardly. Becausethe force on the diaphragm is applied by a fluid, the loading isuniformly distributed across the underlying surface of the diaphragm 68.

As seen in FIGS. 6, 7A and 7B, this causes the strain gauge 70 to becompressed and the strain gauge 72 to be placed in tension. These straingauges 70 and 72 are interconnected in a suitable bridge network (notshown) for temperature compensation and to produce a suitable compositeoutput signal representative of weight.

Referring now to FIG. 8 and FIG. 9, two embodiments of a weight scale ofthe invention suitable for employment of the strain gauge assemblies ofeither FIGS. 1 and 2 or FIG. 6 is shown. As seen in FIG. 8, the weightscale has a housing 88 containing a display 90 for providing a visualindication of weight in response to signals from a suitable electronicadder circuit 91. The electronic adder circuit 91 produces an averageweight signal representative of the average weight or load applied to apair of substantially identical strain gauge assemblies or load modules92. These load modules 92 preferably comprise the load modules or straingauge assemblies shown in FIGS. 1 and 6 and described above, butself-contained load modules of other construction could be successfullyemployed. The housing also contains a DC power supply, such as a drycell battery, which is connected to power the electronic adder 91 bymeans of leads 94. Each of the load modules are likewise connected toelectronic adder 91 by means of leads 96. As seen in FIG. 8, the adder91 and display 90 are contained in a common housing 98. In FIG. 9, theweight scale is substantially identical to that of FIG. 8, except thatthe adder 91 is separate from the display 90 and four substantiallyidentical load modules 92 are employed instead of only two. Electronicadder is connected to the display, preferably a digital electronicdisplay, by means of leads 100.

In both scales of 8 and 9, when employing a load module such as shown inFIG. 1 which contains a switch 34, the switch 34 is connected with thepower supply 94 and interrupts application of power to the electronicadder except when a load exceeding a preselected minimum load, such astwenty pounds, is applied. With plural switches 34, the switches areconnected in series, so that each load module requires a minimum loadbefore the application of power to the electronic adder and display. Anadditional switch 102, associated with electronic adder 91, may beprovided to adjust the adder for calibration purposes.

While particular and preferred embodiments of the invention have beendisclosed, it should be appreciated that numerous variations may be madewith respect thereto without departing from the scope of the inventionas set forth in the following claims. For instance, although aparticular arrangement of movable and non-movable support members andforce transmitting members has been shown, some of the advantages of theinvention could be obtained with other combinations and permutations.

We claim:
 1. In a weight scale having a housing and a display responsiveto a strain gauge signal for visually indicating weight measured by thescale, an improved strain gauge assembly, comprising:a flexible memberwith a strain gauge attached thereto to provide an electrical signal inresponse to the flexing of the flexible member; a foot member inunderlying relationship with the flexible member; a load receivingmember in overlying relationship with the flexible member; a pair ofsupport members connected with the foot member for supporting theflexible member at a pair of spaced locations associated therewith; anda pair of load transmitting members connected with the load receivingmember for transmitting a load therefrom to the flexible member at twolocations spaced from one another and from the pair of locationsassociated with the foot member, at least one of said support membersand load transmitting members having one end pivotally connected to theflexible member to pivot at a fixed location thereof and another endconnected to the associated one of the foot member and load receivingmember for relative lateral movement with respect thereto.
 2. The weightscale of claim 1 in which said movement is translational lateralmovement.
 3. The weight scale of claim 1 in which said relative movementis non-sliding movement.
 4. The weight scale of claim 3 in which saidrelative movement is rocking movement.
 5. The weight scale of claim 1 inwhichone of said support members is mounted for movement relative to thefoot member, and one of the load transmitting members is mounted formovement relative to the load receiving member.
 6. The weight scale ofclaim 5 in which one of said support members is fixedly attached to thefoot member.
 7. The weight scale of claim 5 in which one of said loadreceiving members is fixedly attached to the load receiving member. 8.The weight scale of claim 1 in which one of said support members andload receiving members has a relative narrow connection portionengageable with the flexible member at a fixed location thereof and abase portion connected to its associated foot or force receiving membersfor relative movement therealong.
 9. The weight scale of claim 8 inwhich said base portion has an arcuate surface for rolling translationalmovement.
 10. The weight scale of claim 9 in which said base portion isfixedly mounted to the connection portion and said rolling motionimparts a pivotal motion to said connection portion.
 11. The weightscale of claim 8 in which said base portion has a rocker surface forrocking movement.
 12. The weight scale of claim 8 in which one of saidsupport members and one of said loading transmitting members have a baseportion with a rocker for rocking movement thereof.
 13. The weight scaleof claim 10 including means connected with the load receiving member,flexible member and foot member for retaining them together in theabsence of a load.
 14. The weight scale of claim 13 in which saidretaining means includes a plurality of straps for holding the flexiblemember to the foot member and the load receiving member, respectively,in the absence of a load.
 15. The weight scale of claim 13 in whichsaidflexible member has grooves in a surface thereof, and said retainingmeans includes a plurality of straps which fit into the grooves,respectively, to retain the flexible member, foot member and loadreceiving members against substantial relative lateral movement in theabsence of a load.
 16. The weight scale of claim 1 in combinationwithanother improved strain gauge assembly substantially identical tosaid first mentioned strain gauge assembly contained with the housing, acircuit responsive to the strain gauge signals from both of the straingauge assemblies for producing a weight signal representative of thetotal load applied thereto, and means for applying the weight signal tothe display to provide an indication of the total weight.
 17. In aweight scale having a housing and a display responsive to a strain gaugesignal for visually indicating weight measured by the scale, an improvedstrain gauge assembly, comprising:a flexible member with a strain gaugeattached thereto to provide an electrical signal in response to theflexing of the flexible member; a foot member in underlying relationshipwith the flexible member; a load receiving member in overlyingrelationship with the flexible member; a pair of support membersconnected with the foot member for supporting the flexible member at apair of spaced locations associated therewith; a pair of loadtransmitting members connected with the load receiving member fortransmitting a load therefrom to the flexible member at two locationsspaced from one another and from the pair of locations associated withthe foot member; and means connected with the load receiving member,flexible member and foot member for retaining them together in theabsence of a load, said retaining means including a plurality ofretaining members, one of said retaining members being attached to theload receiving member and engaging the flexible member adjacent one ofthe load transmitting members, and another of said retaining membersbeing attached to the foot member and engaging the flexible memberadjacent one of support members.
 18. The weight scale of claim 17includinganother retaining member attached to the load receiving memberand engaging the flexible member for holding it thereto adjacent theother load transmitting member, and another retaining member attached tothe foot member and engaging the flexible member for holding it theretoadjacent the other support member.
 19. A strain gauge assembly,comprisinga foot member; a load receiving member; a flexible member witha strain gauge attached thereto; and means for interconnecting theflexible member with the foot member and the load receiving memberincluding a rigid interconnecting member movably mounted between theflexible member and at least one of the foot member and the loadreceiving member for lateral movement relative thereto, saidinterconnecting member having a relatively narrow end pivotallyconnected to the flexible member at a fixed connection point thereon ata preselected fixed distance from the strain gauge, and another end forlaterally moving along the surface of the at least one of the footmember and the load receiving member to which it is connected inresponse to relative lateral movement of the fixed connection pointduring bending of the flexible member in response to application of aload.
 20. The strain gauge assembly of claim 19 in which saidinterconnecting means includes another interconnecting member spacedfrom said movably mounted interconnecting member and in engagement withsaid elongate flexible member and said at least one of the foot memberand the load receiving member to which is connected the movably mountedinterconnecting member.
 21. The strain gauge assembly of claim 20 inwhich said other interconnecting member is fixedly mounted to the one ofsaid foot member and load receiving member to which is connected saidmovably mounted interconnecting member.
 22. The strain gauge assembly ofclaim 19 in which said movably mounted interconnecting member is mountedto the foot member for rocking movement relative thereto.
 23. The straingauge of claim 19 in which said movably mounted interconnecting memberis mounted to said load receiving member for rolling movement relativethereto.
 24. The strain gauge of claim 19 in which said flexible memberhas a slot at said fixed connection point for receipt of said relativelynarrow end of the movably mounted interconnecting member.
 25. The straingauge assembly of claim 24 in which said other end of theinterconnecting member has an arcuate surface for rolling lateralmovement.
 26. The strain gauge assembly of claim 19 in which saidinterconnecting member is a vertical load transmitting member whichinterconnects the load receiving member and the flexible member totransmit a load to said elongate flexible member from the load receivingmember.
 27. The strain gauge assembly of claim 26 including anothervertical load transmitting member which is fixedly mounted to one ofsaid load receiving member and said flexible member and spaced from saidmovably mounted load transmitting member by a preselected amount greaterthan said preselected distance.
 28. The strain gauge assembly of claim27 including another vertical support member which is fixedly mounted toone of said foot member and the flexible member and spaced from saidmovably mounted support member by a preselected amount greater than saidpreselected distance.
 29. The strain gauge assembly of claim 25including another load transmitting member spaced from said movablymounted load transmitting member by another preselected amount less thansaid preselected amount.
 30. The strain gauge assembly of claim 29 inwhich said support members are located between said load transmittingmembers.
 31. The strain gauge assembly of claim 30 in which the movablymounted support member is mounted adjacent said fixedly mounted loadtransmitting member.
 32. The strain gauge assembly of claim 26 in whichsaid movably mounted load transmitting member is mounted to the footmember for rocking movement relative thereto.
 33. The strain gaugeassembly of claim 25 including another movably mounted load transmittingmember interconnecting the load receiving member and the flexible memberand mounted to the load receiving member for non-sliding movementrelative thereto.
 34. The strain gauge assembly of claim 33 in whichsaid movably mounted load transmitting member is mounted to the loadreceiving member for rocking movement relative thereto.
 35. The straingauge assembly of claim 33 in which movably mounted load transmittingmember is mounted to the flexible member for pivotal movement relativethereto.
 36. The strain gauge assembly of claim 35 in which said movablymounted load transmitting member is mounted to the load receiving memberfor rocking movement relative thereto.
 37. The strain gauge assembly ofclaim 33 in which said flexible member has a central plane extendingtherethrough and all of said support members and said load transmittingmembers are mounted to slots of said flexible member which extend to alocation spaced from said plane.
 38. The strain gauge of claim 19 inwhich said interconnecting member is a support member whichinterconnects the flexible member and the foot member and supports theflexible member against a vertical load above the foot member.
 39. Thestrain gauge assembly of claim 19 in which said flexible member has acentral plane and said movably mounted interconnecting member is engagedtherewith at a location spaced from said plane.
 40. The strain gaugeassembly of claim 39 in which said flexible member has a notch extendingtherein to a preselected distance from said central plane and saidinterconnecting member is received within said notch.
 41. The straingauge assembly of claim 19 including a second strain gauge attached tosaid flexible member opposite said first mentioned strain gauge.
 42. Thestrain gauge assembly of claim 19 in combination with a meter forproducing an indication of the amount of strain imposed on said straingauge.
 43. A strain gauge assembly, comprising:a foot member; a flexiblemember overlying said foot member havinga pair of opposite horizontalupper and lower surfaces substantially equidistant from a centralhorizontal neutral plane thereof, a first notch extending upwardly awayfrom said foot member into the lower one of said surfaces to within anon-zero preselected distance from said central plane, and a secondnotch extending downwardly toward said foot member into the other ofsaid surfaces to within another non-zero preselected distance from saidcentral plane; a strain gauge mounted to one of said horizontalsurfaces; a support member underlying the flexible member and mounted tosaid foot member and extending into said first notch to support saidflexible member at said one non-zero preselected distance from thecentral neutral plane intermediate the lower one of said surfaces andthe central plane; and means directly unidirectionally transmitting avertically directed load to said flexible member includinga forcereceiving member in overlying relationship with said flexible member andsaid foot member, and a force transmitting member mounted to said forcereceiving member and extending downwardly into said second notch totransmit vertical force received by the force receiving member directlyto the flexible member at said other non-zero preselected distance fromthe central neutral plane intermediate the upper one of said surfacesand the central plane.
 44. The strain gauge assembly of claim 43 inwhichsaid flexible member hasa third notch extending upwardly into thelower one of said horizontal surfaces to within said one preselectednon-zero distance from said central plane, and a fourth notch extendingdownwardly into the upper one of said upper surface to within said otherpreselected non-zero distance from the central neutral plane, andincluding a second support member mounted to said foot member andextending upwardly into said third notch to support the flexible memberat said one preselected non-zero distance from the central neutralplane, and in which said load transmitting means includes a second forcetransmitting member mounted to an under surface of said force receivingmember and extending downwardly into said fourth notch to directlytransmit downward force received by the force receiving member to theflexible member at said other preselected non-zero distance from thecentral plane.
 45. The strain gauge assembly of claim 44 in whichthesecond and fourth notches are spaced from one another by a firstpreselected distance, said first and third notches are separated fromone another by a second preselected distance which is less than saidfirst preselected distance, and said one and the other preselecteddistances from the central plane are equal to each other.
 46. The straingauge assembly of claim 45 in which the first and second notches areseparated from one another by a third preselected distance and the thirdand fourth notches are separated from one another by a fourthpreselected distance which is substantially equal to said thirdpreselected distance.
 47. The strain gauge assembly of claim 46 in whichthe strain gauge is mounted to the one horizontal surface between thefirst and third notches.
 48. The strain gauge assembly of claim 47including a second strain gauge mounted to the other of said horizontalsurfaces opposite said first mentioned strain gauge.
 49. In a weightscale having a housing, a power supply and a weight indicator responsiveto a strain gauge, the improvement being a self-contained strain gaugemodule mounted within the housing, comprising:an elongate forcereceiving member having an open face opposite a main horizontal wallbetween a pair of spaced, downwardly extending sidewalls; an elongateframe member having an open face opposite a main horizontal wall betweena pair of upwardly extending sidewalls; an elongate flexible member witha strain gauge attached to a horizontal surface thereof for measuringflexing in a vertical plane; and means connected with the main walls ofthe frame member and force receiving member for mounting the flexiblemember in force receiving relationship therebetween and for protectionthereof by both of said pairs of sidewalls, said sidewalls overlappingto protectively contain the flexible member therebetween in adjacentparallel relationship therewith when mounted in force receivingrelationship between the main walls, said mounting means includinga pairof spaced, rigid support members connected between the frame member forsupporting the flexible member sufficiently above the main wall of theframe at a pair of spaced locations to enable downward flexing whenweight is applied to the main wall of the force receiving member, a pairof spaced, rigid force transmitting members connected between theflexible member and the frame receiving member for supporting the forcereceiving member above the main wall of the force receiving member attwo spaced locations to directly transmit a vertical weight load fromthe main wall of the force receiving member to the flexible member atsaid two locations to cause flexing of the flexible member.
 50. Thestrain gauge assembly of claim 49 in which the pair of sidewalls of oneof said frame member and the force receiving member is slideablyreceived between the pair of sidewalls of the other of said frame memberand the force receiving member.
 51. The strain gauge assembly of claim49 in which the elongate sidewalls of the frame member are between andadjacent the elongate sidewalls of the force receiving member andadjacent elongate sidewalls of the flexible member.
 52. The strain gaugeassembly of claim 49 in which each of said frame member and forcereceiving member have a second pair of sidewalls at the end thereofwhich interconnect and extend in a direction transverse to the elongatesidewalls.
 53. The strain gauge assembly of claim 49 including a switchconnected with the strain gauge and mounted to one of said frame memberand force receiving member and protectively enclosed therebetween. 54.The strain gauge assembly of claim 53 in which said switch is actuatedby relative vertical movement between the frame member and the forcereceiving member.
 55. A strain gauge sub-assembly, comprising:anelongate, flexible rectangular member having a relatively wider pair ofsurfaces equidistant from a central neutral plane thereof and arelatively narrower pair of surfaces interconnecting the relativelywider surfaces; a strain gauge mounted to one of said pair of relativelywider surfaces, and a pair of notches in each of said pair of relativelywider surfaces extending into the flexible member to a non-zeropreselected distance from the central neutral plane.
 56. The straingauge sub-assembly of claim 55 in which said notches have asubstantially V-shaped cross section.
 57. The strain gauge sub-assemblyof claim 55 in which the distance between the pair of notches of one ofsaid pair of surfaces is greater than the distance between the notchesof the other of said pair of surfaces.
 58. The strain gauge sub-assemblyof claim 55 in which said pairs of notches are symmetrically locatedwith respect to the elongate center of the flexible member.
 59. Thestrain gauge assembly of claim 55 in which all of said preselecteddistances are equal to each other.
 60. The strain gauge sub-assembly ofclaim 55 including another strain gauge mounted to the other of saidrelatively wider pair of surfaces opposite the first mentioned straingauge.
 61. In an electric weight scale having a housing and a displaymounted to the housing for providing a visual indication of weight, theimprovement comprising:a plurality of separate self contained loadmodules contained within the housing and each of which includes a straingauge for sensing weight, each of said modules including its own switchactuated only in response to receipt of a weight thereby to enableprovision of a visual indication of weight, an electric adder connectedwith each of the strain gauges of said plurality of load modules forproducing a total weight signal proportional to the total weight sensedby the strain gauges; and means for connecting the total weight signalto the display to cause visual display of the total weight representedthereby.
 62. In an electric weight scale having a housing and a displaymounted to the housing for providing a visual indication of weight, theimprovement comprising:a plurality of separate self contained loadmodules contained within the housing and each of which includes a straingauge for sensing weight, said plurality of load modules including twoload modules located alongside one another and spaced a distance fromone another by a distance substantially equal to the distance between aperson's feet when standing normally, each one of said two load modulesproviding a weight signal in response to the force applied thereto byone foot independently of the force applied by the other foot to theother module, an electric adder connected with each of the strain gaugesof said plurality of load modules for producing a total weight signalproportional to the total weight sensed by the strain gauges; and meansfor connecting the total weight signal to the display to cause visualdisplay of the total weight represented thereby.